Prosecutors: DNA links alleged weapon to slain Morristown boy

Morris County jurors deciding the fate of accused child killer Porfirio Jimenez got a science lesson today about a lesser-known type of DNA.

Prosecutors say that DNA links hair stuck on the suspected murder weapon, a gardening tool, to 10-year-old Walter Contreras Valenzuela, who was savagely beaten to death seven years ago.

Mitochondrial DNA was extracted from two hairs, one taken from a metal-pronged cultivator and the other from one of the boy's boots. The garden tool and boots were found near Walter's body, discovered on a Morristown riverbank on May 22, 2001.

While nuclear DNA is unique to every individual, DNA from mitochondria, the cells' energy producers, is not. Still, the prosecution argued similarities between Walter's mitochondrial profile and the mitochondrial DNA from the hair on the gardening tool bolstered the claim that the boy was killed with the cultivator. The hair on the boot also matched Walter's profile.

Authorities claim Jimenez, 43, met up with Walter at a playground 1 1/2 blocks from the boy's Abbett Avenue home on May 20, 2001, giving the boy food to feed ducks. The two then headed to a fishing spot about a mile away off Cory Road, where police say Jimenez tried to rape the boy and savagely beat him to cover up the crime.

On Tuesday, Edward Crooker from the Morris County sheriff's criminal investigation section, showed jurors how the shape of the round, hollow end of the cultivator matched marks left on Walter's head.

"It's a match. He was struck with this instrument," Crooker said.

The prosecution also said Jimenez' nuclear DNA in seminal fluid found inside the boy's underpants. State Police forensic scientist Raymond Klama testified today in state Superior Court in Morristown that he found evidence of spermatozoa in the back of the boy's underpants.

The defense team admits Jimenez tried to have sex with Walter, but claim he became psychotic when he realized what he had done and was insane when he killed the boy. A psychiatrist for the defense claims Jimenez believed the boy was the devil and had to be killed, although he conceded the former day laborer never told him that.

Psychiatrist Arnaldo Apolito based that assessment on a comment Jimenez made to an investigator, "The devil walks with people sometimes."